From 86669872fb166cf4c41fd4b136c48244f726befa Mon Sep 17 00:00:00 2001
From: Timotej Lazar <timotej.lazar@araneo.org>
Date: Thu, 10 Sep 2015 22:38:58 +0200
Subject: Add Hint classes for normal and sequence hints

---
 server/hints.py          | 29 +++++++++++++++++++++++++++++
 server/prolog_session.py | 43 +++++++++++++++++++++++++++----------------
 2 files changed, 56 insertions(+), 16 deletions(-)
 create mode 100644 server/hints.py

diff --git a/server/hints.py b/server/hints.py
new file mode 100644
index 0000000..c70c596
--- /dev/null
+++ b/server/hints.py
@@ -0,0 +1,29 @@
+# coding=utf-8
+
+import server.user_session
+
+# Hint.instantiate takes a hint object (dictionary) to be sent to the client
+# and sets additional fields based on previously sent hints.
+
+# Simple hint: don't do anything.
+class Hint(object):
+    def __init__(self, name):
+        self.name = name
+
+    def instantiate(self, hint, prev_hints):
+        pass
+
+# Hint sequence: each time this hint is sent, increase the message index until
+# the last message is reached, then repeat that.
+class HintSequence(Hint):
+    def __init__(self, name, length):
+        self.name = name
+        self.length = length
+
+    def instantiate(self, hint, prev_hints):
+        index = 0
+        for prev_hint in prev_hints:
+            if prev_hint['id'] == self.name:
+                index = max(index, prev_hint['indices'][0]+1)
+        index = min(index, self.length-1)
+        hint['indices'] = [index]
diff --git a/server/prolog_session.py b/server/prolog_session.py
index 8a7b635..3e48cbc 100644
--- a/server/prolog_session.py
+++ b/server/prolog_session.py
@@ -42,6 +42,7 @@ class PrologSession(object):
         self._access_lock = threading.Lock()
         self._engine_id = None
         self._problem_id = -1
+        self._sent_hints = []
 
     def run(self, code):
         with self._access_lock:
@@ -92,28 +93,24 @@ class PrologSession(object):
     def hint(self, sid, problem_id, program):
         session = server.user_session.get_session_by_id(sid)
         language, problem_group, problem = Problem.get_identifier(problem_id)
+        language_module = problems.load_language(language, 'common')
         problem_module = problems.load_problem(language, problem_group, problem, 'common')
 
-        # If compilation fails just return compiler messages.
-        engine_id, output = prolog.engine.create(code=program)
-        if engine_id is not None:
-            prolog.engine.destroy(engine_id)
-        if 'error' in map(operator.itemgetter(0), output):
-            errors_msg = '\n'.join(['{}: {}'.format(m_type, m_text) for m_type, m_text in output])
-            return [{'id': 'syntax_error', 'args': {'messages': errors_msg}}]
-
-        # Otherwise try problem-specific hints.
-        if hasattr(problem_module, 'hint'):
+        hints = []
+        if hasattr(language_module, 'hint'):
+            hints = language_module.hint(program)
+        if not hints and hasattr(problem_module, 'hint'):
             hints = problem_module.hint(session, program)
-            if hints:
-                return hints
+        if not hints:
+            hints = [{'id': 'no_hint'}]
 
-        # Finally return a generic "try thinking a bit" message.
-        return [{'id': 'no_hint'}]
+        self._instantiate_and_save_hints(language_module, problem_module, hints)
+        return hints
 
     def test(self, sid, problem_id, program):
         session = server.user_session.get_session_by_id(sid)
         language, problem_group, problem = Problem.get_identifier(problem_id)
+        language_module = problems.load_language(language, 'common')
         problem_module = problems.load_problem(language, problem_group, problem, 'common')
 
         solved_problems = [p for p in CodeqUser.solved_problems(session.get_uid(), language)
@@ -123,9 +120,23 @@ class PrologSession(object):
 
         try:
             n_correct, n_all = problem_module.test(session, code)
-            return [{'id': 'test_results', 'args': {'passed': n_correct, 'total': n_all}}]
+            hints = [{'id': 'test_results', 'args': {'passed': n_correct, 'total': n_all}}]
         except AttributeError as ex:
-            return [{'id': 'test_results', 'args': {'passed': 0, 'total': 0}}]
+            hints = [{'id': 'test_results', 'args': {'passed': 0, 'total': 0}}]
+
+        self._instantiate_and_save_hints(language_module, problem_module, hints)
+        return hints
+
+    # Add hint parameters (such as message index) based on hint class. Append
+    # the finalized hints to the list of sent hints.
+    def _instantiate_and_save_hints(self, language_mod, problem_mod, hints):
+        with self._access_lock:
+            for hint in hints:
+                for mod in [language_mod, problem_mod]:
+                    if hasattr(mod, 'hint_defs') and hint['id'] in mod.hint_defs:
+                        hint_def = mod.hint_defs[hint['id']]
+                        hint_def.instantiate(hint, self._sent_hints)
+            self._sent_hints.extend(hints)
 
     def run_for_user(self, user_id, problem_id, program, query):
         """A "shorthand" method to start a Prolog session, load correct solutions of all user's solved
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